Z31T ECU Swap Questions
05-07-2009, 02:15 PM
#127
NisTuner
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Join Date: Sep 2005
Location: Cleveland, Ohio
Posts: 2,800
As far as I can tell the 114 pin is just for the ECU memory, but at the same time that may be another power source that could be needed. It would only take a moment so plug a pin into 114 and run it to a constant. When you convert it back to the 280ZX ecu do you change the chopper wheel in the distributor back? Or do you leave it? Check to make sure the chopper wheel is positioned correctly and make sure the the dizzy swap was done right.
http://forums.hybridz.org/showthread.php?t=114687
One thing that I could think of, what did you do with the connector for the dropping resistors? Did you disconnect that, bypass it, leave it hooked up? If that's not connected or bypassed properly you won't be getting voltage to your injectors.
http://forums.hybridz.org/showthread.php?t=114687
One thing that I could think of, what did you do with the connector for the dropping resistors? Did you disconnect that, bypass it, leave it hooked up? If that's not connected or bypassed properly you won't be getting voltage to your injectors.
05-07-2009, 08:23 PM
#130
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Join Date: Jul 2008
Posts: 92
no dice..
I'll explain what happened because this is just odd...
Everything is hooked up correctly. I have fuel pressure, spark, the ecu is lit up, maf is wired correctly and here's what happens.
I turn the key and the ecu lights up red and green. when i try to start it when the car has been sitting for a few hours it will start for 1 second and die. After that it will crank over and over with no change.
Also when the car cranks the ecu lights go off and then come back on after i let off the ignition. Is that normal?
I smell gas like crazy after a bit of cranking so i'm assuming everything is working ok on the fpr side.
Could it be a jenked ecu? I don't know anybody around here that has a 300zx to test it out on so it's pretty much a crapshoot at this point.
I'll explain what happened because this is just odd...
Everything is hooked up correctly. I have fuel pressure, spark, the ecu is lit up, maf is wired correctly and here's what happens.
I turn the key and the ecu lights up red and green. when i try to start it when the car has been sitting for a few hours it will start for 1 second and die. After that it will crank over and over with no change.
Also when the car cranks the ecu lights go off and then come back on after i let off the ignition. Is that normal?
I smell gas like crazy after a bit of cranking so i'm assuming everything is working ok on the fpr side.
Could it be a jenked ecu? I don't know anybody around here that has a 300zx to test it out on so it's pretty much a crapshoot at this point.
05-08-2009, 12:17 AM
#132
NisTuner
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Join Date: Sep 2005
Location: Cleveland, Ohio
Posts: 2,800
did you try flipping the chopper wheel in the distributor around? I know that it's possible to have that wheel flipped the wrong way. I didn't experience what happens, but I know that the car won't idle. You could try that. When you go back to the 81 ECU, do you go back to the front cover mounted CAS or do you run it with the CAS in the distributor? Also one other thing that I thought of, for the wiring from the fuel pump relay you did use the black wire off the green relay behind the glovebox right? Also make sure that you got the black wire and not possibly the black/white wire. One thing I've encountered is with alot of these old wires, they have a tendency to be dirty and sometimes you won't notice the stripe on them until you go a little ways in.
05-08-2009, 10:02 AM
#133
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For the life of me I don't see the fpr 1 behind the glovebox.
I checked my chilton and all they really identified was fpr2 thats located around the battery.
It's probably a dumb question but could it possibly be the relay thats behind the battery and screwed to the fender wall? I remember the relay that plugs into it on my 83 was green, however the one on my 81 harness is brown.
I checked my chilton and all they really identified was fpr2 thats located around the battery.
It's probably a dumb question but could it possibly be the relay thats behind the battery and screwed to the fender wall? I remember the relay that plugs into it on my 83 was green, however the one on my 81 harness is brown.
05-08-2009, 10:28 AM
#134
It's to the right of the glovebox & behind a bunch of wiring. It's hard to see w/ the dash still in.
How did you run pin 108 to the fuel pump relay if you haven't yet found the fuel pump relay?
How did you run pin 108 to the fuel pump relay if you haven't yet found the fuel pump relay?
05-08-2009, 11:37 AM
#136
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Join Date: Jul 2008
Posts: 92
ecu lights up, still doesn't start and the fuel pump stays on until the key is turned off.
here is how everything is wired.
new pin 12 / cut 33 and connected to pin 12
new pin 34 - connected to + coil
new pin 3 - connected to - coil
new pin 114 - connected to ign +
pin 108 connected to black wire running to fpr in glovebox
ecu pin 16 connected to 108
16 wire is connected to ign +
Swapped 81 cas with 83 280zx dizzy and z31 chopper disk.
here is how everything is wired.
new pin 12 / cut 33 and connected to pin 12
new pin 34 - connected to + coil
new pin 3 - connected to - coil
new pin 114 - connected to ign +
pin 108 connected to black wire running to fpr in glovebox
ecu pin 16 connected to 108
16 wire is connected to ign +
Swapped 81 cas with 83 280zx dizzy and z31 chopper disk.
05-08-2009, 11:48 AM
#137
ecu lights up, still doesn't start and the fuel pump stays on until the key is turned off.
here is how everything is wired.
new pin 12 / cut 33 and connected to pin 12
new pin 34 - connected to + coil
new pin 3 - connected to - coil
new pin 114 - connected to ign +
pin 108 connected to black wire running to fpr in glovebox
ecu pin 16 connected to 108
16 wire is connected to ign +
Swapped 81 cas with 83 280zx dizzy and z31 chopper disk.
here is how everything is wired.
new pin 12 / cut 33 and connected to pin 12
new pin 34 - connected to + coil
new pin 3 - connected to - coil
new pin 114 - connected to ign +
pin 108 connected to black wire running to fpr in glovebox
ecu pin 16 connected to 108
16 wire is connected to ign +
Swapped 81 cas with 83 280zx dizzy and z31 chopper disk.
pin 3 is only needed if you are using the Z31 ignitor
pin 16 goes to air regulator (as discussed before).
I think you have some wiring issues.... I suggest looking at my Excel spreadsheet again.
05-08-2009, 11:53 AM
#138
NisTuner
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Join Date: Sep 2005
Location: Cleveland, Ohio
Posts: 2,800
Again not sure if it's enough to make a difference, but pin 114 is supposed to be connected to a constant 12v. Not an ignition switched 12v, as it's meant to save ECU memory etc. I guess it's possible that the 81 has a different colored Fuel Pump Relay. At least your fuel pump works when the key is on. Mine did the same thing with the 84-85 ECU and would just continuously run with the ignition switched to ON. Just to make sure. when you pulled the glovebox out there were 3 relays right? The FPR you need is the one farthest in the back, the hardest to get too...
Anyway here's my two things to try. Again make sure you have your dropping resistors plugged in, connect pin 114 to a constant 12V, and if that still doesn't work open the distributor back up and take that little wheel that spins on the crank angle sensor and try flipping that over. Like I said if that's in there the wrong way the car will not idle. If you're able to run the 280ZX ECU on the CAS the way it is in the distributor, it could just simply be that the way it reads it on the 280ZX was just not as advanced as the Z31 and can allow for error? Seeing as you said that you can get it to start-up at least for a moment makes me think the ECU is fine, but possibly receiving an incorrect signal from the CAS. Once you get pin 114 hooked up to a constant 12v you can mess with it for a bit and then see if you're getting any specific error codes. Like I said though, try flipping that chopper wheel around.
As for pin 16 I think what he's saying is that he connected pin 16 to the old 108 wire which runs to the air regulator. Not actually connected it to the wire running from the FPR to pin 108. You can run pin 34 to + coil terminal as it gets fed an ignition +12v. I also ran pin 3 to the negative coil. That's how I ran my Z31 setup at first. Eventually I just went ahead and spliced the pin 34 wire into the wire going to the positive coil terminal and the pin 3 wire into the wire going to the negative coil so I wouldn't run the risk of frying my ECU from using my Mallory.
One other thing I started to think was that it's possible your MAF is connected improperly. Maybe a wire got switched or something, but I do know that one time I stupidly left the MAF unplugged in my car. It started up and ran. Just terribly and wouldn't rev over 2000 RPM.
Anyway here's my two things to try. Again make sure you have your dropping resistors plugged in, connect pin 114 to a constant 12V, and if that still doesn't work open the distributor back up and take that little wheel that spins on the crank angle sensor and try flipping that over. Like I said if that's in there the wrong way the car will not idle. If you're able to run the 280ZX ECU on the CAS the way it is in the distributor, it could just simply be that the way it reads it on the 280ZX was just not as advanced as the Z31 and can allow for error? Seeing as you said that you can get it to start-up at least for a moment makes me think the ECU is fine, but possibly receiving an incorrect signal from the CAS. Once you get pin 114 hooked up to a constant 12v you can mess with it for a bit and then see if you're getting any specific error codes. Like I said though, try flipping that chopper wheel around.
As for pin 16 I think what he's saying is that he connected pin 16 to the old 108 wire which runs to the air regulator. Not actually connected it to the wire running from the FPR to pin 108. You can run pin 34 to + coil terminal as it gets fed an ignition +12v. I also ran pin 3 to the negative coil. That's how I ran my Z31 setup at first. Eventually I just went ahead and spliced the pin 34 wire into the wire going to the positive coil terminal and the pin 3 wire into the wire going to the negative coil so I wouldn't run the risk of frying my ECU from using my Mallory.
One other thing I started to think was that it's possible your MAF is connected improperly. Maybe a wire got switched or something, but I do know that one time I stupidly left the MAF unplugged in my car. It started up and ran. Just terribly and wouldn't rev over 2000 RPM.
Last edited by duowing; 05-08-2009 at 12:02 PM.
05-08-2009, 12:27 PM
#139
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Join Date: Jul 2008
Posts: 92
duo,
there were 3 relays and the furthest back was my green one. I cut the black wire and connected pin 108 directly to the fpr via that wire.
you are right about the 16 pin to the old 108, thats how i have it hooked up.
Everything looks to be hooked up right on my end and it's the same old thing. When i first turn the car over when it's been sitting all night i get a 1/2 -1 sec period where it micro starts then dies. after that it's notta unless it sits for another 4+ hours. the disc inside the dizzy is on the right way so that shouldn't be an issue.
I'm just starting to think the ecu was a piece of crap when i got it. I'm seriously debating about either shelving the z indefinitely or looking at megasquirt.
I'll triple check everything over again for the 10th time but i'm under the assumption that it's faulty equip that i'm battling.
Also, just making sure here because it's the only wire i'm not 100% sure about. #16 blue/red harness side runs to 12v ignition correct?
there were 3 relays and the furthest back was my green one. I cut the black wire and connected pin 108 directly to the fpr via that wire.
you are right about the 16 pin to the old 108, thats how i have it hooked up.
Everything looks to be hooked up right on my end and it's the same old thing. When i first turn the car over when it's been sitting all night i get a 1/2 -1 sec period where it micro starts then dies. after that it's notta unless it sits for another 4+ hours. the disc inside the dizzy is on the right way so that shouldn't be an issue.
I'm just starting to think the ecu was a piece of crap when i got it. I'm seriously debating about either shelving the z indefinitely or looking at megasquirt.
I'll triple check everything over again for the 10th time but i'm under the assumption that it's faulty equip that i'm battling.
Also, just making sure here because it's the only wire i'm not 100% sure about. #16 blue/red harness side runs to 12v ignition correct?
Last edited by midwest83280z; 05-08-2009 at 12:36 PM.
05-08-2009, 01:08 PM
#140
NisTuner
Thread Starter
Join Date: Sep 2005
Location: Cleveland, Ohio
Posts: 2,800
Yeah the pin 16 blue wire with a red stripe goes to a 12v ignition source. One thing I'm wondering is, what color wire do you happen to have that connected to. One problem you could possibly be having is it could be connected to a 12v ignition source, but I believe it needs to be a source that stays switched on even while starting. If you have it hooked to a wire that doesn't have voltage when cranking that could cause an issue. Like I said make sure you hook pin 114 up to a constant 12v. Also I'm just curious how you know that the chopper wheel is in the right way? Anyway what was recommended in the one swap was to take the pin 16 blue w/ red stripe and connect it into the black w/ white striped wire going to the fuel pump modulator that sits up above the ECU.
That could be my guess, is that the chopper wheel is on backwards or that something that's supposed to still have voltage is losing it when cranking the car. You could always try putting the key to ON and then using a screwdriver or something to jump the posts on the starter to see if that makes any difference as if you were losing voltage to something when you shouldn't.
It's possible that the ECU is bad, but overall it's hard to say. It just sounds like there's something simple that's just being missed. I understand how frustrating this can get, but at least you can always go back to the 280ZX ecu and run the car that way.
That could be my guess, is that the chopper wheel is on backwards or that something that's supposed to still have voltage is losing it when cranking the car. You could always try putting the key to ON and then using a screwdriver or something to jump the posts on the starter to see if that makes any difference as if you were losing voltage to something when you shouldn't.
It's possible that the ECU is bad, but overall it's hard to say. It just sounds like there's something simple that's just being missed. I understand how frustrating this can get, but at least you can always go back to the 280ZX ecu and run the car that way.
05-08-2009, 01:17 PM
#141
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Join Date: Jul 2008
Posts: 92
lol man this day sucks.. my 2 year old is being a monster, the z is kicking my A$$ and i'm going completely nutty
After i get done banging my head against a wall & the gf gets home I'll check my ignition source to make sure it's constant while the car cranks. I do notice that when the car turns over my ecu lights shut off then turn back on about 1/4 sec after i lay off. Not sure if thats normal or not..
After i get done banging my head against a wall & the gf gets home I'll check my ignition source to make sure it's constant while the car cranks. I do notice that when the car turns over my ecu lights shut off then turn back on about 1/4 sec after i lay off. Not sure if thats normal or not..
05-08-2009, 02:08 PM
#142
Registered User
Join Date: Jul 2008
Posts: 92
the ecu is chunked... I actually waved down some ricer kid in town that had a 300 and we plugged in the ecu.. va va va va va va va... lol same crap.
the place i bought it from is refunding my money so i'm just going to sell my 300z maf and look into ms.
sorry for all the questions. you guys rock though and i appreciate all your help!
the place i bought it from is refunding my money so i'm just going to sell my 300z maf and look into ms.
sorry for all the questions. you guys rock though and i appreciate all your help!
09-09-2010, 05:42 PM
#145
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Join Date: Sep 2010
Location: Finland
Posts: 9
I'm new to forum and immediately come to you for a advice. I have installed L28ET with z31 ecu and z31 harness to my s30, but I have a problem. I'm not getting spark and injector pulse is missing too. I have checked the connections. I have tried with two different power transistor, but no luck. When I put key to on-position Ecu lights up, but when starting the lights go off. Is this right? Also the fuel pump works right away when I turn the key to ON-position.
These are connection I have made:
3 / pwr.transistor b/w wire
5 / pwr.transistor blue wire
9 / ignition position, which is actived only when starting
16 / fuse-> ignition key position, which is actived when key is in ON-position and START-position
20 / fuel pump relay(coil side)->ignition key position, which is actived only when starting
34 / Coil + and fuse->ignition key position, which is actived when key is in ON-position and START-position
108/ fuel pump->fuse->which is actived when key is in ON-position and START-position and Fuel pump relay->earth
Also two fusible links I have changed to fuses and the fuses are ok. Today I checked the wires from injectors to ecu and to the battery. They are ok. Also I flipped the chopper wheel upside to make sure that isn't the problem. Any hints?
These are connection I have made:
3 / pwr.transistor b/w wire
5 / pwr.transistor blue wire
9 / ignition position, which is actived only when starting
16 / fuse-> ignition key position, which is actived when key is in ON-position and START-position
20 / fuel pump relay(coil side)->ignition key position, which is actived only when starting
34 / Coil + and fuse->ignition key position, which is actived when key is in ON-position and START-position
108/ fuel pump->fuse->which is actived when key is in ON-position and START-position and Fuel pump relay->earth
Also two fusible links I have changed to fuses and the fuses are ok. Today I checked the wires from injectors to ecu and to the battery. They are ok. Also I flipped the chopper wheel upside to make sure that isn't the problem. Any hints?
09-09-2010, 07:12 PM
#146
^^^ Welcome to ZDriver! 
What instructions did you follow for the Z31 ecu swap? Because your wiring is wack!
Check out my 280ZXT to Z31T ecu/maf swap document (schematics and Excel file of ecu pins): https://www.zdriver.com/forums/attac...9&d=1238179990 If the ZIP file requires a password, it's turbo.
You don't do anything w/ ecu pin 5, 9, and 20... you don't touch or change them at all. Pin 3 is ONLY used if you are also using the Z31 coil. Pin 16 is swapped with the harness wire from pin 108, and now controls the air regulator. Pin 34 connects to + ignition source (the black w/ white stripe from fuel pump module works best). Pin 108 wire is run to the green fuel pump relay ground wire (black).
If you are using an 81 L28ET wire harness, you must also add a power wire to pin 114.
Lastly, make sure the coil bracket is securely grounded, otherwise the ignitor won't have a connection for spark.
I just completed an L28ET Z31 ecu/maf swap into my 76 280z this spring: https://www.zdriver.com/forums/240z-260z-280z-motor-swaps-non-v8-269/l28et-s30-tucked-like-stock-only-better-pic-heavy-30516/
I laid out the stock harness, hooked it up, started it to make sure all connections were good, removed the harness, performed the wiring upgrades for the ecu swap, and re-installed.
What instructions did you follow for the Z31 ecu swap? Because your wiring is wack!
Check out my 280ZXT to Z31T ecu/maf swap document (schematics and Excel file of ecu pins): https://www.zdriver.com/forums/attac...9&d=1238179990 If the ZIP file requires a password, it's turbo.
You don't do anything w/ ecu pin 5, 9, and 20... you don't touch or change them at all. Pin 3 is ONLY used if you are also using the Z31 coil. Pin 16 is swapped with the harness wire from pin 108, and now controls the air regulator. Pin 34 connects to + ignition source (the black w/ white stripe from fuel pump module works best). Pin 108 wire is run to the green fuel pump relay ground wire (black).
If you are using an 81 L28ET wire harness, you must also add a power wire to pin 114.
Lastly, make sure the coil bracket is securely grounded, otherwise the ignitor won't have a connection for spark.
I just completed an L28ET Z31 ecu/maf swap into my 76 280z this spring: https://www.zdriver.com/forums/240z-260z-280z-motor-swaps-non-v8-269/l28et-s30-tucked-like-stock-only-better-pic-heavy-30516/
I laid out the stock harness, hooked it up, started it to make sure all connections were good, removed the harness, performed the wiring upgrades for the ecu swap, and re-installed.
Last edited by NismoPick; 09-09-2010 at 07:15 PM.
09-10-2010, 06:34 AM
#147
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Join Date: Sep 2010
Location: Finland
Posts: 9
I just followed the schematics from FSM. And I'm only using z31 wiring harness nothing else.
Why wouldn't I change pins 9, 5 and 20?
9 gives start signal from the ignition.
5 is needed for the power transistor
20 is needed for the fuel pump.
I forgot to mention that I'm also using walbro fuel pump and also I don't use exhaust gas sensor, because the wiring harness comes from a version which doesn't have it.
Why wouldn't I change pins 9, 5 and 20?
9 gives start signal from the ignition.
5 is needed for the power transistor
20 is needed for the fuel pump.
I forgot to mention that I'm also using walbro fuel pump and also I don't use exhaust gas sensor, because the wiring harness comes from a version which doesn't have it.
09-10-2010, 09:24 AM
#150
Interesting... I did not know an US Z31's came w/o an O2 sensor.
I still see problems w/ your wiring...
#3 you state is connected to b/w (+12v power)? I have it listed as the negative power.
#5 is a green black wire.
#16 controls the air regulator.
#108 is fuel pump relay ground signal.
Is that how you have these wires hooked up? Did you check out that ZIP file I posted?
I still see problems w/ your wiring...
#3 you state is connected to b/w (+12v power)? I have it listed as the negative power.
#5 is a green black wire.
#16 controls the air regulator.
#108 is fuel pump relay ground signal.
Is that how you have these wires hooked up? Did you check out that ZIP file I posted?
